c++: Optimize in maybe_clone_body aliases even when not at_eof [PR113208]

c++: Optimize in maybe_clone_body aliases even when not at_eof [PR113208]

This patch reworks the cdtor alias optimization, such that we can create
aliases even when maybe_clone_body is called not at at_eof time, without trying
to repeat it in maybe_optimize_cdtor.

2024-05-15  Jakub Jelinek  <jakub@redhat.com>
	    Jason Merrill  <jason@redhat.com>

	PR lto/113208
	* cp-tree.h (maybe_optimize_cdtor): Remove.
	* decl2.cc (tentative_decl_linkage): Call maybe_make_one_only
	for implicit instantiations of maybe in charge ctors/dtors
	declared inline.
	(import_export_decl): Don't call maybe_optimize_cdtor.
	(c_parse_final_cleanups): Formatting fixes.
	* optimize.cc (can_alias_cdtor): Adjust condition, for
	HAVE_COMDAT_GROUP && DECL_ONE_ONLY && DECL_WEAK return true even
	if not DECL_INTERFACE_KNOWN.
	(maybe_clone_body): Don't clear DECL_SAVED_TREE, instead set it
	to void_node.
	(maybe_clone_body): Remove.
	* decl.cc (cxx_comdat_group): For DECL_CLONED_FUNCTION_P
	functions if SUPPORTS_ONE_ONLY return DECL_COMDAT_GROUP if already
	set.

	* g++.dg/abi/comdat3.C: New test.
	* g++.dg/abi/comdat4.C: New test.